In prior art percussion devices strokes are generated by means of a reciprocating percussion piston, which is typically driven hydraulically or pneumatically and in some cases electrically or by means of a combustion engine. A stress wave is created in a tool, such as a drill rod, when the percussion piston strikes an impact end of either a shank or the tool.
A problem with prior art percussion devices is that the reciprocating motion of the percussion piston generates dynamic acceleration forces that make the equipment difficult to control. At the same time as the percussion piston accelerates in the striking direction, the body of the percussion device tends to move in the opposite direction, thereby decreasing the pressing force of the drill bit or the tool tip on the material to be treated. To maintain the pressing force of the drill bit or the tool against the material to be treated sufficiently high, the percussion device must be pushed towards the material with a sufficient force. This additional force must then be taken into account in the support structures of the percussion device, as well as elsewhere, which increases not only the size and mass of the equipment but also the manufacturing costs thereof. The mass of the percussion piston causes inertia that restricts the frequency of the reciprocating motion of the percussion piston and thereby its impact frequency, although the latter should be significantly raised from its current level in order to achieve a more efficient performance. However, with current solutions this leads to a considerable deterioration in operating efficiency, which is why it is not possible in practice. Further, in prior art percussion devices it is quite difficult to control the percussion power according to drilling conditions. Further still, prior art knows percussion devices in which the stress wave is generated by rapidly compressing the tool against the material to be broken, without delivering a stroke.